1. Field of the Invention
This invention relates to a high 1,4-cis polybutadiene-polyurethane copolymer and a preparation method thereof. More specifically, the present invention relates to a method for preparing a high 1,4-cis polybutadiene-polyurethane copolymer that includes preparing a high 1,4-cis polybutadiene-polyurethane copolymer using a copolymer of a high 1,4-cis polybutadiene excellent in elasticity due to its linear molecular structure with high cis stereoregularity and a polyurethane excellent in abrasion resistance, and a rare earth catalyst, and adding an isocyanate compound and an alcohol.
2. Related Prior Art
Methods for preparing a high 1,4-cis polybutadiene using a rare earth catalyst are disclosed in European Patents Nos. 0,011,184 (Bayer AG) and 0,652,240 (Bayer Inc.), and U.S. Pat. Nos. 4,260,707 (Sylvester) and 5,017,539 (Jenkins et al.). In these methods, a high 1,4-cis polybutadiene is prepared by using a neodymium carboxylate compound, an alkylaluminum compound and a Lewis acid in the presence of a non-polar solvent.
U.S. Pat. No. 5,428,119 (Knauf et al.) discloses a method for preparing a high 1,4-cis polybutadiene using a rare earth carboxylate and alkylaluminum compounds such as R1AlCl2, R12AlCl or R13Al2Cl3 (where R1 is C8-C12 alkyl) and R22AlH (where R2 is C2-C6 alkyl).
UK Patent No. 2,002,003 (ANIC S.p.A.) and U.S. Pat. No. 4,429,089 (Pedretti et al.) suggest a method for preparing a high 1,4-cis polybutadiene using AlR2X (where R is hydrogen or alkyl; and X is hydrogen, alkoxy or alkoxy sulfide), alkyl aluminum, and a neodymium compound.
European Patent No. 0,092,270 (Enichem Polimeri S.p.A.) and U.S. Pat. No. 4,444,903 (Carbonaro et al.) propose a method for preparing a high 1,4-cis polybutadiene using a catalyst system comprising a rare earth metal, alkyl aluminum, and t-alkyl halogen. U.S. Pat. No. 4,736,001 (Carbonaro et al.) describes a method for preparing high 1,4-cis polybutadiene using the above-mentioned catalyst system without a solvent.
In addition, U.S. Pat. No. 4,699,962 (Hsieh et al.) discloses a synthetic method of high 1,4-cis polybutadiene using a catalyst system prepared by mixing a neodymium hydride compound, a chloride compound and an electron-donating ligand, and then adding an alkyl aluminum compound.
European Patent No. 375,421 (Enichem Elastomers Limited) and U.S. Pat. No. 5,017,539 (Jenkins et al.) also describe a synthetic method of high 1,4-cis polybutadiene by aging a neodymium compound, an organohalide compound and an organoaluminum compound at 0° C. or less.
In applications of the high 1,4-cis polybutadiene, the terminal of the polybutadiene is modified so as to control viscosity or affinity to additives in post-admixture. More specifically, the terminal of polybutadiene is modified epoxy or isocyanate by using the living property of the neodymium catalyst as mentioned in, for example, WIPO Publication No. 02/36615 (Applied Molecular Evolution, Inc.), and European Patents Nos. 0,713 885 (Nippon Zeon Co., Ltd) and 0,0267 675 (Japan Synthetic Rubber Co., Ltd.).
A low 1,4-cis polybutadiene-polyurethane copolymer that is the copolymer of low 1,4-cis polybutadiene and polyurethane is disclosed in documents (Makrmol. Chem. 1983, 651; Adv. Polym. Sci. 2002, 21, 25; Plasty a kaucuk 2002, 39, 68). In the cited documents, the polybutadiene is a hydroxyl-modified polybutadiene synthesized by using an anionic polymerization catalyst. More specifically, the polybutadiene is a low 1,4-cis polybutadiene having a 1,4-vinyl content of about 35%, a 1,4-vinyl content of about 30% and a 1,4-cis content of about 10 to 30%, with a small molecular weight of about 3000. The synthetic method of low 1,4-cis polybutadiene-polyurethane copolymer is comprised of three steps that include polymerization of polybutadiene with an anionic catalyst such as butyl lithium, adding an epoxy compound to prepare hydroxyl polybutadiene; and adding an isocyanate compound to yield low 1,4-cis polybutadiene-polyurethane copolymer. Low 1,4-cis polybutadiene-polyurethane copolymer thus synthesized is used as a resin modifier.